Johann Christian Bach (05/09/1735 - 01/01/1782), a German/English composer, born in Leipzig, Germany, worked for a lot of years in London and died there. He is the youngest son of Johann Sebastian Bach and Anna Magdalena Bach. His nick-name: "the London Bach".

Messa de' morti is for 8 voices and orchestra. It contains:
- Requiem
- Te decet hymnus
- Kyrie
"Introitus" and "Kyrie" are extant as a pair, although they may originally have existed as separate entities; may have been intended, along with an 8-pt. "Dies irae", as part of a projected complete requiem for double chorus, to be realized in stages over a period of time.
From the late 17th century onwards, mainly through the contributions of leading opera composers such as Feo, Galuppi, Hasse, Pergolesi, Jommelli, Gassmann, Cimarosa and Gossec, individual movements of the requiem became gradually larger, the orchestration richer and the solo vocal writing more elaborate. In some cases, single texts, usually the 'sequence' and the 'responsory', were set separately, either as independent motets or as a means of providing vivid contrast within chanted forms of the funeral service. Examples include an impressive Dies irae for soloists, double chorus and orchestra by Lully (1684); and one with similar scoring by J.C. Bach (1757).